HUMMING-BIRD 443 



dwarfed. Still the manus, in comparison with the other parts of 

 the wing, is so long that the term Macrochires is not wholly in- 

 accurate. The affinity of the TrocMlidx and Cypselida^, once pointed 

 out, became obvious to most careful and unprejudiced investigators, 

 though there are a few systematists who refuse to admit its 

 validity.^ More than this, it is confirmed by an examination of 

 other osteological characters. The " lines," as a boat-builder would 

 say, upon which the skeleton of each form is constructed are pre- 

 cisely similar, only that whereas the bill is very short and the head 

 wide in the Swifts, in the Humming-birds the head is narrow and 

 the bill long — the latter developed to an extraordinary degree in 

 some of the Trochilidse, rendering them the longest-billed birds 

 known. ^ Prof, Huxley considers these two Families, together 

 with the Capimulgidm (Nightjar), to form the division Cypselo- 

 morphse — one of the two into which he separated his larger group 

 yEgithognathse. However, the most noticeable portion of the 

 Humming-bird's skeleton is the sternum, which in proportion to 

 the size of the bird is enormously developed both longitudinally 

 and vertically, its deep keel and posterior protraction affording 

 abundant space for the powerful muscles which drive the wings in 

 their rapid vibrations as the little creature poises itself over the 

 flowers where it finds its food.^ 



So far as is known, all Humming-birds possess a protrusible 

 tongue, in conformation peculiar among the Class Aves, though to 

 some extent similar to that member in the Picidx (Woodpecker)'* 

 — the " horns " of the HYOID apparatus upon Avhich it is seated 

 being greatly elongated, passing round and over the back part of 

 the head, near the top of which they meet, and thence proceed 

 forward, lodged in a broad and deep groove, till they terminate in 

 front of the eyes. But, unlike the tongue of the Woodpeckers, 

 that of the Humming-birds consists of two cylindrical tubes, taper- 

 ing towards the point, and forming two sheaths which contain the 

 extensile portion, and are capable of separation, thereby facilitating 

 the extraction of honey from the nectaries of flowers, and with it, 

 what is of far greater importance for the bird's sustenance, the 



1 Especially Dr. Shufeldt {Proc. Zool. Soc. 1885, pp. 886-915, pis. lviii.-lxi., and 

 Jourii. Linn. Soe. xx. pp. 299-394, pis. xxi.-xxiv.) On the other side may be 

 cited the views of Mr. Lucas (Auk, 1886, pp. 444-451). 



^ Thus Domnastes cnsifer, in which the bill is longer than both head and 

 body together. 



^ This is especially the case with the smaller species of the group, for the 

 larger, though shooting with equal celerity from place to place, seem to flap 

 their wings with comparatively slow but not less powerful strokes. The differ- 

 ence was especially observed with respect to the largest of all Humming-birds, 

 Patagona gigas, by Mr. Darwin. 



■* The resemblance, so far as it exists, must be merely the result of analogical 

 function, and certainly indicates no affinity between the Families. 



